S912XEG384J3VA Datasheet, PDF (77/1324 Pages) Freescale Semiconductor, Inc – MC9S12XEP100 Reference Manual Covers MC9S12XE Family

Chapter 1 Device Overview MC9S12XE-Family
The state of the ROMCTL signal is latched into the ROMON bit in the MMCCTL1 register on the rising
edge of RESET. The state of the EROMCTL signal is latched into the EROMON bit in the MMCCTL1
register on the rising edge of RESET.
Table 1-12. Chip Modes and Data Sources
Chip Modes
MODC
MODB
MODA
ROMCTL EROMCTL
Data Source⁽¹⁾
Normal single chip
1
0
0
X
X
Internal
Special single chip
0
0
0
Emulation single chip
0
0
1
X
0
Emulation memory
X
1
Internal Flash
Normal expanded
1
0
1
0
X
External application
1
X
Internal Flash
Emulation expanded
0
1
1
0
X
External application
1
0
Emulation memory
1
1
Internal Flash
Special test
0
1
0
0
X
External application
1
X
Internal Flash
1. Internal means resources inside the MCU are read/written.
Internal Flash means Flash resources inside the MCU are read/written.
Emulation memory means resources inside the emulator are read/written (PRU registers, Flash replacement, RAM, EEPROM,
and register space are always considered internal).
External application means resources residing outside the MCU are read/written.
1.4.1.1 Normal Expanded Mode
Ports K, A, and B are configured as a 23-bit address bus, ports C and D are configured as a 16-bit data bus,
and port E provides bus control and status signals. This mode allows 16-bit external memory and
peripheral devices to be interfaced to the system. The fastest external bus rate is divide by 2 from the
internal bus rate.
1.4.1.2 Normal Single-Chip Mode
There is no external bus in this mode. The processor program is executed from internal memory. Ports A,
B,C,D, K, and most pins of port E are available as general-purpose I/O.
1.4.1.3 Special Single-Chip Mode
This mode is used for debugging single-chip operation, boot-strapping, or security related operations. The
background debug module BDM is active in this mode. The CPU executes a monitor program located in
an on-chip ROM. BDM firmware waits for additional serial commands through the BKGD pin. There is
no external bus after reset in this mode.
1.4.1.4 Emulation of Expanded Mode
Developers use this mode for emulation systems in which the users target application is normal expanded
mode. Code is executed from external memory or from internal memory depending on the state of
ROMON and EROMON bit. In this mode the internal operation is visible on external bus interface.
MC9S12XE-Family Reference Manual Rev. 1.25
Freescale Semiconductor
77